Woven fabric



Jan. 17, 1950 H. cRAwsHAw 2,494,646

WOVEN FABRIC Filed July 27, '1945 \wxvaw urt HARRY C. RAM/5M W PatentedJan. 17, 1950 FFICE WOVEN FABRIC Harry Crawsliaw, London, England,assignor, by mesne assignments, to Celanese Corporation of America, acorporation of Delaware Application July 27, 1945, Serial No. 607,301

In Great Britain August 2, 1944 7 Claims. 1

This invention relates to woven fabrics and is particularly concernedwith heavy, canvasdike fabrics designed for use in belts and belting,for example conveyor belts and power transmission belts.

In conveyor belts and belts for power transmission having a basis ofwoven fabric, difliculty frequently arises in making a strong and securejoint between the ends of the belt. The stress in the continuous part ofthe belt is carried by the warp yarns running parallel to the length ofthe belt but at the point where the ends are joined, the stress mustalso be taken by the weft yarns near the ends and by the cohesionbetween these weft yarns and the warp yarns. This commonly necessitatesthe use of a greater quantity of weft, to provide the necessary strengthat the joint, than would otherwise be desirable. But for the joint, itwould be desirable to keep the weight and number of the weft threadsdown to a minimum both to facilitate manufacture, and also to make fulluse ofthe strength of the warp yarns and to give a fabric which will notstretch unduly in use. It is an object of the present invention toprovide a belting fabric which, without containing an undue quantity ofweft, enables a strong joint to be made between the ends of a beltcontaining the fabric.

According to the present invention, a belting fabric comprises heavywarp yarns and weft yarns woven together and is provided, at shortintervals along the length of the fabric, with a weft of several timesthe weight of the weft employed elsewhere in the fabric. The heavy weftsthus occurring at intervals along the length of the fabric arepreferably in the form of several picks (for example from four to ten)inserted,

over substantially the whole width of the fabric, in the same shed byappropriate arrangements in the plan or system by which the warps areshedded.

With a belting fabric of this character it is possible to arrange that aheavy pick or a group of picks is presented to the belt-fastening meansin each of the ends that are to be joined together. This is found to agive a much higher tear-out strength at the fastening than when auniformly woven fabric containing the same weight of weft is employed.Or, for the same or even a somewhat higher tear-out strength the totalweight of weft employed in the fabric may be reduced, enabling betteruse to be made of the tensile strength of the warp yarns. Thus the ratioof the total weight of weft to the total weight of warp in the fabric,instead of being from about 2 0.6 to 0.35 depending chiefly on theweight of the fabric (heavier fabrics tending to have a lower ratio) mayin the fabrics of the present invention be reduced to from about 0.5 to0.2.

The invention is of particular advantage in belts in which a fabricfoundation, generally in the form of several layers of fabric securedtogether by means of rubber or other flexible adhesive, is provided witha covering of rubber or like flexible material to give a smooth surfaceof the desired texture and consistency. The ends of such belts may bejoined by various means, e. g. a simple lacing passing through holespunched in the belt at a little distance from each of the ends to bejoined, or a metal fastener presenting a series of hooks or points toeach of the ends of the belt. Care should be taken to include, withinthe scope of the fastening means at each of the ends to be joined, aheavy weft in the majority, and preferably in each, of the fabric layersof the belt. This can be done by making the scope of the fastener ateach end to be joined at least as great as the distance between theheavy picks or the groups of picks in the fabric. This distance may be,for example, from /2" to 2" according to the character of the belt.

The invention is also of particular advantage where the yarns employedin the fabric, and particularly in the warp, are made of continuousartificial filaments, e. g. filaments of high tensile strength made bystretching filaments of cellulose acetate or other organic derivative ofcellulose in the presence of wet steam or other agent adapted tofacilitate stretching. Where the filaments that are stretched are ofcellulose acetate or other ester of cellulose, they are preferablysaponified after being stretched. Continuous filament yarns, andparticularly yarns of highly stretched continuous filaments, have a veryslippery character so that there is a marked tendency for weft yarnsclose to the cut end of the fabric to slip. In addition warp yarns whichare of high tensile strengthon account of having been stretched areparticularly liable to a diminution of their effective strength throughbeing woven with too dense a weft. Both of these difliculties areovercome or substantially reduced by the present invention. Theinvention may also be applied with advantage to belts containing otherkinds of yarn, e. g. to belts in which the warp yarns or the weft yarnor both are of linen, cotton or artificial staple fibres made by cuttingcontinuous filaments into staple lengths.

While the belting fabrics to which the present invention relates may beclassified generally as heavy fabrics, this class of fabrics covers afairly wide range of weights. Thus, it includes a light canvas, havingwarp yarns of about 500 denier spaced at about 50 ends per inch, wovenwith a weft of, say, 350 denier at an average spacing of 40 picks perinch. n the other hand, a heavy fabric may be woven having warp yarns of5000 denier or more, spaced at 22 ends per inch or less according to thedenier, and woven with a weft of, say, 2500 denier at an average spacingof about 12 picks per inch. The distribution of weft between the heavyand the light picks can be arranged so that from a quarter, up to asmuch as two-thirds of the weight of the weft is in the heavy picks, andthe remainder uniformly distributed along the length of the fabric.

A belting fabric according to the present invention, and belts madetherefrom, may be employed for most purposes in which joined belts arerequired. One particularly important application of the invention is forconveyor belts as used underground in coal mines. Belts used for thispurpose work under very severe conditions giving rise to frequentbreakage, often require changes of length as the circumstances of theiruse alter, and need to be joined by fastenings of the simplest type.Each of these factors makes the belts and belting fabrics according tothe present invention, particularly advantageous.

The following are given as examples of a belting fabric in accordancewith the invention:

Example I The fabric is made with a warp of continuous filament yarnmade by stretching continuous filament cellulose acetate yarn in thepresence of wet steam to ten times its original length and thensaponifying the stretched yarn. Each warp yarn is made by doublingtogether three ends each of 1100 denier. The warps are spaced in thefabric at 28 ends per inch. This warp is woven with a weft of similarmaterial, but made by doubling together three ends of about 750 denier.The wefts are inserted in the fabric at an average density of 18 picksper inch but of these 18 picks 12 are inserted in separate sheds and,except at the selvedges, the remaining 6 picks are inserted all in thesame shed. At each of the selvedges, a narrow band of fabric six ends inwidth is formed, in which all the picks are in separate sheds. This isdone in order to secure, at the edges of the fabric, the six picks thatare inserted in a single shed for the remaining and major part of thewidth of the fabric.

In this way a fabric is produced having. across almost the whole of itswidth, a heavy pick, of 6 times the weight of the picks used elsewherein the fabric, occurring once every inch of fabric and alternating witha series of 12 single picks. A comparative test was made between such afabric and a fabric exactly similar except that the wefts were uniformlyspaced in separate sheds. In the test a. cord lacing was passed througha hole punched near the cut edge of the fabric, and a load was appliedto the cord in a fabric strength testing machine. The tear-out strengthin the fabric according to the invention was 412 lbs.. against atear-out strength of only 108 lbs. in the comparative fabric,notwithstanding that the warp-tensile strengths of both fabrics weresubstantially equal at 430 lbs. per inch width.

Example II A belting somewhat lighter than that of Example I is preparedfrom a warp of singles yarns of 2200 denier, spaced in the fabric at 32ends per inch. As in Example I the yarns consist of stretched andsaponified cellulose acetate continuous filaments. The weft yarns are ofthe a same kind and denier as the warp yarns, and are spaced at anaverage density of 18 picks per inch. woven in the same way as inExample I.

In the drawing, Fig. 1, which is a diagrammatic view of a portion offabric near the edge thereof, shows generally the structure of thebelting fabric in accordance with the invention, and agrees in detailwith Examples I and H, and

Fig. 2 is a diagrammatic edge view partly in section of a multi-ply beltin accordance with the invention.

The warps l are as closely spaced as conveniently possible, so as togive the maximum warp strength per inch width of fabric. The wefts areless closely spaced, and comprise single picks 2, groups of 12 whichalternate with heavy multiple picks 3 each consisting of 6 yarn ends. Atthe edges of the fabric, however, for a distance of 6 warp ends 4, allthe weft yarns 2 and 3 are separate so that the weft yarns 3 aresecurely bound at the edges of the fabric at the points 5, in the sameway as the weft yarns 2 at the points 6.

The fabrics described above can be made up into multi-ply belts of fromtwo to six plies or more,

according to the weight of the individual fabric and the desired weightof the product. The individual fabrics are given a friction coating ofrubber; that is they are passed between the two lower bowls of acalender of which the middle bowl carries a thin layer of rubber stockand rotates faster than the lower bowl, so that the stock is ground intothe fabric, which travels at the same speed as the lower bowl. Ifdesired, the frictioned fabric may be given a further coating, or skimcoating by a calendaring operation in which the two lower bowls rotatewith the same surface speed as the fabric passing between them, and inwhich a thin layer of rubber carried by the middle bowl is caused toadhere firmly to the friction coating. The coating or coatings of rub-45 ber thus imparted serve to bind the several layers of fabric togetherin the multi-ply belt. The assembled and adhering layers are given anexternal coating of rubber or the like of substantial thickness, e. g.from to extending round 50 the edges as well as over the surfaces of theassembled layers. A -ply belt of this kind is shown diagrammatically inFig. 2 in which the individual fabrics are indicated at I, and the heavywefts therein at 8. The external coating of rub- 55 ber 9 extends roundthe edge of the belt as indicated at "I. Thin layers of rubber at H,between the fabrics 'I, firmly unite the several fabrics together, therubber being ground into the fabric as indicated above.

Having described my invention, what I desire to secure by Letters Patentis:

l. A belting fabric comprising single wefts and heavy and closely spacedwarp yarns woven together, and having at short intervals along thelength of the fabric and extending at least across the whole width ofthe fabric between the selvedge bands thereof, grouped wefts, insertedin one shed, of the yarn employed as the single wefts elsewhere in thefabric.

2. A belting fabric comprising single wefts and heavy and closely spacedwarp yarns woven together, and having at short intervals along thelength of the fabric, grouped wefts, inserted over the greater part ofthe width of the fabric in one 75 shed, of the yarn employed as thesingle wefts elsewhere in the fabric, said latter wefts being inserted,over a narrow selvedge band at each edge of the fabric, all in differentsheds.

3. A belting fabric consisting of continuous filament yarns of hightensile strength made by stretching continuous filaments in the presenceof a softening agent for the substance of the filaments, said fabricscomprising weft yarns and heavy and closely spaced warp yarns woventogether, and having at short intervals along the length of the fabricand extending at least across the whole width of the fabric between theselvedge bands thereof, an isolated weft of several times the weight ofthe weft employed elsewhere in the fabric.

4. A belting fabric consisting of continuous filament yarns of hightensile strength made by stretching continuous filaments of celluloseacetate in the presence of moist steam and saponifying the stretchedfilaments, said fabric comprising weft yarns and heavy and closelyspaced warp yarns woven together, and having at short intervals alongthe length of the fabric and extending at least across the whole widthof the fabric between the selvedge bands thereof, an isolated weft ofseveral times the weight of the weft employed elsewhere in the fabric.

5. A belting fabric consisting of continuous filament yarns of hightensile strength made by stretching continuous filaments of celluloseacetate in the presence of moist steam and saponifying the stretchedfilaments, said fabric comprising single wefts and heavy and closelyspaced warp yarns woven together, and having at short intervals alongthe length of the fabric, grouped wefts. inserted over the greater partof the width of the fabric in one shed, of the yarn employed as thesingle wefts elsewhere in the fabric, said latter wefts being inserted,over a narrow selvedge band at each edge of the fabric, all in differentsheds.

6. Belts and belting materials comprising a plurality of layers, unitedtogether, of belting fabric comprising single wefts and heavy andclosely spaced warp yarns woven together, and having at short intervalsalong the length of the fabric, grouped wefts, inserted over the greaterpart of the width of the fabric in one shed, of the yarn employed as thesingle wefts elsewhere in the fabric, said latter wefts being inserted,over a narrow selvedge band at each edge of the fabric, all in differentsheds.

7. Belts and belt materials comprising a plurality of layers, unitedtogether, of belting fabric consisting of continuous filament yarns ofhigh tensile strength made by stretching continuous filaments ofcellulose acetate in the presence of moist steam and saponifying thestretched filaments, said fabric comprising single wefts and heavy andclosely spaced warp yarns woven together, and having at short intervalsalong the length of the fabric, grouped wefts, inserted over the greaterpart ofthe width of the fabric in one shed, of the yarn employed as thesingle wefts elsewhere in the fabric, said latter wefts being inserted,over a narrow selvedge band at each edge of the fabric, all in differentsheds.

HARRY CRAWSHAW.

REFERENCES crrsn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 21,481 Bredt Sept. 14, 185851,436 Downie Dec. 12, 1865 718,499 Mitchelsen Jan. 13, 1903 1,794,624Kastner Mar. 3, 1931 2,096,835 Amyot Oct. 26, 1937 2,128,764 Smith et alAug. 30, 1938 2,207,862 Henschke July 16, 1940 2,270,154 Whittier Jan.13, 1942 2,355,635 Dubilier Aug. 15, 1944 FOREIGN PATENTS Number CountryDate 122,076 Great Britain Jan. 16, 1919 402,965 Great Britain Dec. 14,1933

